During the forthcoming year studies on the effect of vasodilators on both coronary and ventricular dynamics will be continuted and hopefully completed. These studies will specifically look at the effects of nitroprusside under conditions of myocardial ischemia and nitroglycerin in both normal and ischemic hearts. In addition, studies are being initiated to examine the cardiac, coronary and peripheral effects of ionized calcium levels in both normal and ischemic hearts. Studies are also being initiated on the effects of a variety of cardiac active agents on pulmonary hypertension as represented by the Laks dog model. Studies will also be initiated in relation to the effects of various pharmacologic agents on myocardial perfusion as assessed through Thallium-201 scanning.